1. Field
One or more embodiments described herein relate to a display device and method for driving the same.
2. Description of the Related Art
The performance of displays must increase as information technology evolves. Flat panel displays have been developed in pursuit of this goal. One type of flat panel display, known as an organic light emitting diode (OLED) display, has pixels which output light based on a recombination of electrons and holes in corresponding active layers. Displays of this type have demonstrated relatively fast response speed, low-voltage driving and power consumption, and excellent viewing angle.
One type of OLED display includes a plurality of pixels disposed in a matrix form, a scan driver for supplying scan signals to scan lines of the display panel, a data driver for supplying data voltages to data lines of the display panel, and a power supply source for supplying a plurality of power voltages to the display panel. The power voltages may include a high-potential voltage, a low-potential voltage, and a reference voltage.
Each pixel includes an OLED, a driving transistor for controlling drain-source current according to a data voltage supplied to a gate electrode thereof, and a scan transistor for supplying a data voltage of a data line to the gate electrode of the driving transistor in response to a scan signal of a scan line. The OLED emits light according to the drain-source current of the driving transistor.
The reference voltage is a voltage supplied to the gate electrode of the driving transistor, before the data voltage is supplied to the gate electrode of the driving transistor. That is, the gate electrode of the driving transistor is initialized to the reference voltage before the data voltage is supplied.
However, the reference voltage may be influenced by noise in the display panel. Consequently, the reference voltage supplied from the power supply source may include noise. As a result, the gate electrode of the driving transistor in each pixel may not be initialized to a voltage different from the reference voltage supplied from the power supply source. This may cause a voltage different from the data voltage to be charged in the gate electrode of the driving transistor in each pixel. Consequently, the OLED in each pixel emits light with a luminance different from the luminance corresponding to the data voltage. That is, each pixel expresses a gray scale value different from the gray scale value corresponding to the data voltage, as a result of noise in the display panel. Picture quality is therefore lowered.